It may not be surprising if DL's current oldest A320s retire due to rising maintenance costs rather than cycles/hours. And even that could still be years from now.
I was under the impression that aircraft that were otherwise performing efficiently were typically retired when they were scheduled for a D check, or a "heavy maintenance visit" (HMV) and the cost of the HMV check was higher than the residual value of the aircraft. I thought that was typically the third D check. The aircraft was usually sold in the third world.
I'm no expert, but this may be largely true. However, seems I recall at least some DL MD-88s have been retired even though they could have received at least one more C-check. The MD-88 that was struck by the tug at ATL earlier this year was declared a WO and later scrapped at Atlanta (it was suppose to be one of the last 88s to retire and may have already had ADS-B installed
). A second MD-88s that was about to be retired was instead given a C-check to take the place of the other 88.
Is there a suttle difference between a D-check and a HMV? Do different aircraft have different time gaps between HMVs?
I thought that maximum cycles or flight hours were almost never reached.
Of course, the likes of DC-8s and 707s in decades past had relatively short careers (even if the UPS DC-8s were roughly 40 years old when finally retired
Even today, planes seem to not come overly close to running out of cycles/hours. True, the AF A320-100s cycled out relatively quickly, or at least came close. The -100s only went to 40K cycles and unlike the -200s could not receive the life extension (EFG).
LH has now retired three of their more elderly A320-200s, including two just in the last week or so. The first plane had just shy of 57K cycles and hypothetically could have received one more heavy check and flown the relatively short time to the EFG established limit of 60K cycles. But as Lightsaber touched on earlier, the economics of such a move would probably not be justified. AF and LH running out of cycles (but not hours) is interesting but also indicative of the many shorter routes their A320s flew. This contrasts with DL/NW; had Delta's oldest A320s not received EFG years ago, they would have run out of hours (but not cycles).
Not picking on the A320. It's actually one of my favorite airliners. But until the life extensions arrived, the A320 trailed the 737s and especially the MD-80s in cycles/hours by a good margin.